Transfer of original document images onto a photosensitive surface in copier devices is obtained by several different techniques. For instance, the document is sometimes positioned manually or fed by rollers or belts into a fixed position on a transparent platen so that moving optic elements can scan the image. Other copiers use fixed optics and some form of driven mechanism to move the document past a scan window at a controlled rate. Some fixed-optics copiers use drive rollers or belts to propel the original documents across the scan window either in single passes or recirculating mode such as is taught by U.S. Pat. No. 2,741,960 by Oldenbloom.
The present invention is primarily concerned with fixed optics copiers that have a transparent platen containing carriage on which the document to be copied is placed. The carriage bed is movable in a reciprocating motion over an optical scan window as taught by U.S. Pat. Nos. 2,959,095 by Magnusson and 3,554,640 by Hoskins. It has also been known to include in a single machine combinations of reciprocating carriages and single sheet feeders either as separate units with switchable fixed optics or as an integral unit. The sheet feeder is advantageous for its fast operation but is not compatible with copying books, odd shaped objects or the like which can be copied on reciprocating carriage devices.
With conventional fixed-optics, reciprocating carriage copiers, the document to be copied is manually centered on the platen and a cover closed on the document to hold it in place during carriage movement. This procedure is awkward for the machine operator and reduces the overall operating speed of the machine. Addition of a sheet feeder to the reciprocating carriage machine, either as a separate unit with optic switching or as an integral element in the structure of the carriage bed with mechanisms to appropriately position and control the operation between stationary sheet feed or moving carriage modes, is unacceptable for several reasons. For low cost or compact copiers, such alternatives involve acceptance of added cost and undesirable complexity as well as extended space requirements in some cases. Further, the machine operating procedures become more complex which is particularly undesirable for office copiers.
Unfortunately, the prior art has not suggested any solutions acceptable for low cost copiers whereby single sheets that are automatically or manually fed to a reciprocating carriage in a fixed-optics system are automatically ejected from the carriage at the end of a copy run for a given document. It is the solution to this problem to which this invention is directed.